Jeffrey Carpenter

Test case resources (should be able to be replaced with your own as long as the pixel format and file encoding matches):
  test.bmp RGB8888 (24-bit, BMP)
  test.png ARGB8888 (32-bit, PNG)

This patch reverts [revision 292](https://hg.libsdl.org/SDL_image/log?rev=292) back to the original author's implementation (Eric Wing). The comments made in this revision seem to contradict what is intended; see CGColorSpaceCreateCalibratedRGB [1] and CGColorSpaceCreateDeviceRGB [2] for Apple's API notes. Also note that the revision comments by "Albert" use a test case that is for use with SDL1 -- how this may change things is unknown to me.

1. https://developer.apple.com/library/ios/documentation/GraphicsImaging/Reference/CGColorSpace/index.html#//apple_ref/c/func/CGColorSpaceCreateCalibratedRGB
2. https://developer.apple.com/library/ios/documentation/GraphicsImaging/Reference/CGColorSpace/index.html#//apple_ref/c/func/CGColorSpaceCreateDeviceRGB

  Additional notes
* Tested on Mac OS X 10.10 "Yosemite".
* Has not been tested against iOS, SDL1 or images that have been processed with pre-multiplied alpha.

Build test case:
  clang++ sdl2_image-colorspace-fix.cpp -o sdl2_image-colorspace-fix -framework SDL2 -framework SDL2_image

Run test case to generate my existing data (my baseline / reference):
(output in diag_main.txt, using test.bmp and test.png)

bitmap(0, 0) = ff6e8fbd
png(0, 0) = ff6e8fbd
sdlbmp(0, 0) = 6e90be

bitmap(31, 0) = ff6e8fbd
png(31, 0) = ff6e8fbd
sdlbmp(31, 0) = 6e90be

<snip remaining debug info>

NOTE: ff6e8fbd = R(110) G(143) B(189)
The actual pixel value is 110, 144, 190. SDL_LoadBMP gets it right in both
cases, whereas IMG_Load (ImageIO backend) gets it wrong on both counts.

Apply revert-rev-292.patch:
  hg import revert-rev-292.patch

Rebuild test case, ensuring that we compile and **run** with the proper runtime
search paths for our patched SDL2_image library (I built mine using Xcode project files):

```sh
# man dyld (1)
DYLD_FRAMEWORK_PATH=<my_local_prefix_lib_path> ./sdl2_image-colorspace-fix
```

Comparison output of reference data with patched library:
(output in diag_main.txt, using test.bmp and test.png)

bitmap(0, 0) = ff6e90be
png(0, 0) = ff6e90be
sdlbmp(0, 0) = 6e90be

bitmap(31, 0) = ff6e90be
png(31, 0) = ff6e90be
sdlbmp(31, 0) = 6e90be

<snip remaining debug info>

NOTE: ff6e90be = R(110) G(144) B(190)
The actual pixel values match using both SDL_LoadBMP and IMG_Load. This is the
expected behavior.

  References
1. [Introduction of ImageIO backend](https://forums.libsdl.org/viewtopic.php?p=14777)
2. [Pixel bug in Mac OS X](https://forums.libsdl.org/viewtopic.php?p=30317)
3. [Perhaps again? Pixel bug in Mac OS X](https://forums.libsdl.org/viewtopic.php?t=10013&sid=34e8ef7cf74074039495037c1a077025)